Crank throw adjustment for motion converter mechanisms and the like



y 15, 1952 c. R.-SACCHINI 2,603,105

CRANK THROW ADJUSTMENT FOR MOTION CONVERTER MECHANISMS AND THE LIKE IOriginal Filed Jan. 2'7, 1949 3Q. O 29 6 E E O 3/ 38 36 28 r 3 T O 3 3Q35 @O 4 .36 z fTg 1 i// Z I 3 -25 L3 2.2 36 r VJ"/ I 3 15 g (as 15Gttorneg Patented July 15, 1952 I CRANK THROWADJUSTMENT FOR Mo'rIoNCONVERTER MECHANISMS AND THE LIKE Columbus It. Sacchini, Willoughby,Ohio, assignor to The Marquette Metal Products Company, Cleveland, Ohio,a corporation of Ohio Continuation of application Serial No. 73,142,January 27, 1949. This application June 18, 1949, Serial'No. 100,046

- 1 Claim. l

The invention relates to a motion converter for an electric-motor-drivenwindshield wiper, and particularly to a novel adjustable-throw crankconstruction for a motion converter. The present .application is acontinuation of my prior application Serial No. 73,142, filed January27, 1949, now Patent No. 2,560,000.

Most electric-motor-driven windshield wiper units or installationsemploy reduction gearing between the motor and an oscillating orreciprocating wiper element which latter desirably has essentiallyharmonic motion. Such motion customarily requires some form of scotchyoke or crank and pitman movement connected to and driven by aunidirectionally rotated part such as the power takeofi wheel of thereduction gearing. An important problem in arrangements of the sortoutlined above isto provide a compact and simple crank throw adjustmentfor operation of the scotch yoke or crank and pitman movement wherebythe Wiper stroke can be fixedly set at different amplitudes depending onthe shape and area of the surface to be wiped. Many devices to adjustcrank throw are known but all those with which I am familiar are subjectto one or more disadvantages, examples being complexity and excessivecost; lack of axial compactness; difiiculty of effecting adjustments;likelihood of looseness due to wear of critical parts; uncertainty ofmaintenance of the selected adjustments, and lack of desired or necessartorque transmitting strength particularly when the mechanism served isof small size. Subject invention overcomes thosedisadvantages--indicating the principal objects hereof.

A specific object is to provide a compact crank throw adjustment devicefor mechanisms such as outlined above, wherein a large number of adjustments of small and approximately equal increments are obtainable andwherein the necessary parts can be quickly and positively locked inplace without dependence on friction as when a clamping screw or seriesof screws is or are used to maintain adjustment.

A more specific object is to provide an improved adjustable connectionbetween a crank member (e. g. crank pin) and a rotary operating supportfor the crank member, which connection enables selection of a largenumber of throw adjustments and is rendered effective to maintain theselected adjustment simply by enclosing the crank member and rotarysupport assembly in working position within a suitable housing havingseparable parts adapted to be secured conventionally to each other-whichis to indicate Cir that no special fastening device has to be usedbetween the crank member and its rotary support.

Other objects and features of the invention will become apparent fromthe following description of the two illustrative formsshown in thedrawings wherein:

Fig. 1 is a sectional front elevation of the motion converter hereof, afront cover portion of the mechanism being removed according to line|--l of Fig. 3. Fig. 2 is a sectional rear elevation, taken as indicatedby line 2-2 on Fig. 3. The latter in a sectional plan view asconventionally indicated on Fig. l.

Referring to Figs. 1 to 3, thebody of the converter mechanism unit Icomprises a main body section 2 and front and rear cover sections 3 and4. The cover section 3 forms the principal housing for the adjustablecrank throw mechanism and is removably securedto the section 2 by screwsindicated at 3a Fig. 1 to fix or main tain the crank adjustment as willbe described. Power input to the unit froma suitable electric motor maybe through afiexible drive shaft 5 entering a tubular adapter 6 securedas clearly shown in Fig. 2, the shaft being coupled as at lwith a wormshaft 8 supported in anti-friction bearings 9. The worm it on the shaft8 meshes with a complementary worm wheel H, Figs. 2 and 3, on atransverse shaft [2 supported on bearings l3 and I4 within the section2. Bearing M is ina drive wheel '28 described later. The worm driveaffords a 5:1 reduction to shaft !2.

The principal speed reduction of the unit I is through a gyratoryinternal external gear system which is essentially the same as that ofU. S. Patent 72,792 to Arthur W. Browne. The worm wheel H and a centraldriving gear is of said system have a common key connection with shaftI2, the gear I5 constantly meshing with identical gears 16 rigid withrespective crankoperating shafts I! having parallel cylindrical crank orcam heads 18 projecting from the shafts and eccentrically of theirrespective axes which are fixed by supporting radial and axial thrustbearings i9 and 20 respectively in the body section 2.

The crank or cam heads l8 fit complementary openings in a gyratoryexternally toothed eccentric gear member 22 which is non-.rotatablysupported by the eccentric heads l8. Gear 22 has a full complement ofexternal gear teeth 23. Said teeth mesh continually at one peripheralregion only with internal teeth of an output or rotary power takeoff ordrive wheel 25 of the gearing. The drive wheel 25 is maintained on afixed axis in the casing concentric with the drive shaft l2 by asurrounding bearing sleeve 26. The gyrating gear 22 uniformly advancesthe wheel 25 at a relatively slow rate as determined by the differencein the number of teeth on part of the gyratory gear and wheel 25 (6 inthe illustrated form, affording a reduction of 105:6).

The crank pin of the drive wheel 25, best shown by Fig. 1, is formed bya peripherally serrated circular stub 28 of the drive wheel eccentric tothe drive wheel axis and a circularcrank pin element 29 surrounding thestub 28 and internally serrated to mate the serrations of the stub as at30. One serie of serrations must form a complete annulus. Both arepreferably complete for maximum torque carrying strength and economy ofmanufacture. The crank pin element 29 has an external circularcrank-forming surface 3| which is eccentric to the axis of the serratedopening. Removal of the crank element 29 from its supporting serrations30 (permitted by removal of casing section 3) and replacement of saidelement 29 on the serrations in selected turned positions about the axisof stub 28 enables adjustment of crank throw in small increments (e. g.)from zero to the maximum throw position illustrated.

A zero throw position of the crank element 29 is not actually used inpractice but is provided for (by making the distance by which the disc29 is eccentric to the serrated opening 30 the same as that by which thestub 28 is eccentric to the drive wheel 25) in event an extremely smallangular Wiper travel is required. The eccentric distances mentioned mayof course be dissimilar.

The regular saw-tooth shape of the serration teeth illustrated in thetwo exemplary forms of crank-throw-adjusting mechanism hereof is mainlyby way of example, being of more or less standard form from thestandpoint of manufacture.

The revolving motion of the crank pin element 29 is transmitted to anoscillatory power takeoff or output shaft by a pitman rod 36 having acircular strap portion 36a embracing pin element 29. The rod 36 hasteeth held by a freely rocking yoke 38 pivotally supported on the shaft35, permanently in mesh with teeth of a gear 31 fast on said shaft. Oneend of the shaft 35 extends through a bearing portion 39 of the coversection 3 to support the wiper drive arm (not shown). The oppositeprojecting end portion 40 of the shaft 35 (for parking purposes asexplained in application Serial No. 73,142) has an eccentric cam 4|adjustably fixed thereto as by a screw 42. The cam 4| functions throughan actuator 43 of switch 44 once for each cycle of operation or theshaft 35 to close an electrical parking control circuit not shown.

As shown particularly by Fig. 3 the casing section 3 is made hollow soas to shroud the various parts of the crank mechanism, pitman 36 andyoke 38 when attached to section 2; and concomitantly to expose thoseparts for ease of manipulation thereof as required for crank throwadjustment when the section 3 is removed. The yoke 38, as made apparentin Fig. 1, overhangs the rack portion of the pitman 36 from one sideonly, whereby, when casing section 3 is removed, the pitman can beeasily slid oil the crank pin element 29 and out of engagement with theteeth of pinion 31.

I claim:

In combination a rotary drive member having a disc portion, a casingsection containing the member, and having a shoulder preventing axialmovement of the member in one direction, said section having meansproviding a supporting journal for the member, a generally circular stubprojecting from the disc portion of the drive member eccentric to thejournal axis and having a circular series of uniformly spaced externalserrations, a crank-pin-forming member of circular form having aneccentric generally circular opening formed by internal serrationsmating those of the stub in various turned positions about the axis ofthe stub to provide an adjustable length crank, an output member engagedby the external peripheral surface of the crank-pinforming member, and asecond casing section of hollow form in shrouding relation to the crankand output member assembly, said second section complementing the firstmentioned section and detachably secured thereto, the second section,when in attached position, providing a shoulder holding thecrank-pin-forming member and output member in position on the serratedstub and crank-pin-forming member respectively and approximately againstthe disc portion of the drive member.

COLUMBUS R. SACCHINI.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 447,386 Vuillier Mar. 3, 18912,074,708 Smith Mar. 23, 1937 2,454,881 Michelman Nov. 30, 19482,506,562 Wait May 2, 1950

